Cloud service models

When it comes to cloud computing offerings, there are three main service models to consider for your project:

• IaaS (Infrastructure as a Service): This is the model where the cloud service provider gives you access to infrastructure on the cloud, such as servers (virtual and bare metal), networks, firewalls, and storage devices. You use IaaS when all that you need is for the cloud provider to manage the infrastructure for you and take the hassle and the cost of maintaining it out of your hands. IaaS is used by start-ups and organizations that want full control over their application's layer. Most IaaS offerings come with a dynamic or elastic scaling option, which would scale your infrastructure based on your consumption. This, in effect, saves organizations costs since they only pay for what they use.
• PaaS (Platform as a Service): This is the next layer up from IaaS. PaaS provides the computing platform you need to run your application. PaaS typically includes the operating systems you need to develop your applications, the databases, the web layer (if needed), and the programming language execution environment. With PaaS, you don't have to worry about updates and patches for your application environment; it gets taken care of by the cloud provider. Let's say you wrote a powerful .NET application that you want to see running in the cloud. A PaaS solution will provide the .NET environment you need to run your application, combined with the Windows server operating systems and the IIS web servers. It will also take care of load-balancing and scale for larger applications. Imagine the amount of money and effort you could save by adopting a PaaS platform instead of doing the effort in-house.
• SaaS (Software as a Service): This is the highest layer offering you can obtain as a cloud solution. A SaaS solution is when a fully functional piece of software is delivered over the web. You access SaaS solutions from a web browser. SaaS solutions are typically used by regular users of the software, as opposed to programmers or software professionals. A very famous example of a SaaS platform is Netflix—a complex piece of software hosted in the cloud, which is available to you via the web. Another popular example is Salesforce. Salesforce solutions get delivered to customers through web browsers with speed and efficiency.